U.S. patent application number 10/261505 was filed with the patent office on 2003-04-10 for laminated quarter-wave plate or circularly polarizing plate, liquid-crystal display device using the same and method for producing the same.
This patent application is currently assigned to NITTO DENKO CORPORATION. Invention is credited to Sasaki, Shinichi, Yamaoka, Takashi, Yoshimi, Hiroyuki.
Application Number | 20030067574 10/261505 |
Document ID | / |
Family ID | 19127167 |
Filed Date | 2003-04-10 |
United States Patent
Application |
20030067574 |
Kind Code |
A1 |
Sasaki, Shinichi ; et
al. |
April 10, 2003 |
Laminated quarter-wave plate or circularly polarizing plate,
liquid-crystal display device using the same and method for
producing the same
Abstract
A laminated quarter-wave plate having: a laminate of a
quarter-wave plate and a half-wave plate, wherein: the quarter-wave
plate and the half-wave plate are laminated on each other so that
directions of in-plane slow axes intersect each other; and each of
the quarter-wave plate and the half-wave plate satisfies a relation
Nz=(nx-nz)/(nx-ny)>1.05 in which nx and ny are in-plane main
refractive indices, and nz is a thickness wise refractive index;
and a circularly polarizing plate having: a laminate of a laminated
quarter-wave plate defined above and a polarizer.
Inventors: |
Sasaki, Shinichi;
(Ibaraki-shi, JP) ; Yamaoka, Takashi;
(Ibaraki-shi, JP) ; Yoshimi, Hiroyuki;
(Ibaraki-shi, JP) |
Correspondence
Address: |
SUGHRUE MION, PLLC
2100 PENNSYLVANIA AVENUE, N.W.
WASHINGTON
DC
20037
US
|
Assignee: |
NITTO DENKO CORPORATION
|
Family ID: |
19127167 |
Appl. No.: |
10/261505 |
Filed: |
October 2, 2002 |
Current U.S.
Class: |
349/117 |
Current CPC
Class: |
G02F 1/133638 20210101;
G02F 1/133634 20130101; G02B 5/3083 20130101 |
Class at
Publication: |
349/117 |
International
Class: |
G02F 001/1335 |
Foreign Application Data
Date |
Code |
Application Number |
Oct 3, 2001 |
JP |
P2001-307749 |
Claims
What is claimed is:
1. A laminated quarter-wave plate comprising: a quarter-wave plate;
and a half-wave plate laminated on said quarter-plate, so that
directions of in-plane slow axes of said plates intersect each
other; wherein each of said quarter-wave plate and said half-wave
plate satisfies a relation Nz=(nx-nz)/(nx-ny)>1.05 in which nx
and ny are in-plane main refractive indices, and nz is a
thicknesswise refractive index.
2. A circularly polarizing plate comprising: a laminated
quarter-wave plate according to claim 1 and a polarizer laminated
on said laminated quarter-wave plate.
3. A laminated quarter-wave plate according to claim 1, further
comprising a pressure sensitive adhesive layer provided on at least
one of opposite surfaces of said laminated quarter-wave plate.
4. A circularly polarizing plate according to claim 2, further
comprising a pressure sensitive adhesive layer provided on at least
one of opposite surfaces of said circularly polarizing plate.
5. A liquid-crystal display device comprising: a liquid-crystal
cell; and a laminated quarter-wave plate according to claim 1 and
disposed on at least one of opposite surfaces of said
liquid-crystal cell.
6. A liquid-crystal display device comprising: a liquid-crystal
cell; and a laminated quarter-wave plate according to claim 3 and
disposed on at least one of opposite surfaces of said
liquid-crystal cell.
7. A liquid-crystal display device comprising: a liquid-crystal
cell; and a circularly polarizing plate according to claim 2 and
disposed on at least one of opposite surfaces of said
liquid-crystal cell.
8. A liquid-crystal display device comprising: a liquid-crystal
cell; and a circularly polarizing plate according to claim 4 and
disposed on at least one of opposite surfaces of said
liquid-crystal cell.
9. A method of producing a phase retarder satisfying a relation
Nz=(nx-nz)/(nx-ny)>1.05 in which nx and ny are in-plane main
refractive indices, and nz is a thicknesswise refractive index,
said method comprising the step of: stretching a transparent
polymer film with a thickness of 5 to 500 .mu.m by one of tenter
lateral stretching and biaxial stretching.
Description
[0001] The present application is based on Japanese Patent
Application No. 2001-307749, which is incorporated herein by
reference.
BACKGROUND OF THE INVENTION
[0002] 1. Field of the Invention
[0003] The present invention relates to a laminated quarter-wave
plate or a circularly polarizing plate adapted to compensation for
birefringence, a liquid-crystal display device using the same and a
method for producing the same.
[0004] 2. Description of the Related Art
[0005] As a wave plate capable of providing a retardation of a
quarter wavelength in a wide wavelength range of visible light,
there is known a laminated quarter-wave plate in which a
quarter-wave plate and a half-wave plate produced by uniaxial
stretching are laminated on each other so that directions of
in-plane slow axes of these plates intersect each other. For
example, the laminated quarter-wave plate is widely used for the
purpose of anti-reflection of a liquid-crystal display device
(hereinafter referred to as "LCD").
[0006] A TFT (Thin Film Transfer) drive type twisted nematic (TN)
LCD is widely used in a notebook type personal computer, a monitor,
etc. The TN-LCD has a disadvantage in that the viewing angle
thereof is narrow. A VA- or IPS-LCD capable of providing a wide
viewing angle have been developed and begun to be popularized for
monitor use. The VA- or ISP-LCD, however, needs backlight electric
power because the VA- or ISP-LCD is lower in luminance than the
TN-LCD. Moreover, the VA- or ISP-LCD has been not applied to a
notebook type personal computer requiring low electric power
consumption.
[0007] On the other hand, it is known that frontal luminance of a
multi-domain VA-LCD is improved when the laminated quarter-wave
plate is disposed in one interlayer between a liquid-crystal cell
and a polarizer while a laminated quarter-wave plate capable of
providing circularly polarized light of reverse rotation is
disposed in another interlayer. In this method, it is however
difficult to obtain a wide viewing angle. This problem can be
solved by the related art when a negative uniaxial phase retarder
produced by biaxial stretching and a polarizer are laminated on
each other. There is, however, a disadvantage in that the resulting
film is made thick because a large number of plates must be
laminated as well as production efficiency is made low because a
large number of laminating steps is required.
SUMMARY OF THE INVENTION
[0008] To solve the problems in the related art, on object of the
invention is to provide a quarter-wave plate or a circularly
polarizing plate adapted to compensation for birefringence, a
liquid-crystal display device using the same and a method for
producing the same.
[0009] In order to solve the object, according to the invention,
there is provided a laminated quarter-wave plate having: a laminate
of a quarter-wave plate and a half-wave plate, wherein: the
quarter-wave plate and the half-wave plate are laminated on each
other so that directions of in-plane slow axes intersect each
other; and each of the quarter-wave plate and the half-wave plate
satisfies a relation Nz=(nx-nz)/(nx-ny)>1.05 in which nx and ny
are in-plane main refractive indices, and nz is a thicknesswise
refractive index. Further, according to the invention, there is
provided a circularly polarizing plate having: a laminate of a
laminated quarter-wave plate defined above and a polarizer.
[0010] Further, according to the invention, there is provided a
pressure sensitive adhesive agent-including laminated quarter-wave
plate having: a laminated quarter-wave plate defined above; and a
pressure sensitive adhesive layer provided on at least one of
opposite surfaces of the laminated quarter-wave plate.
[0011] Further, according to the invention, there is provided a
pressure sensitive adhesive agent-including circularly polarizing
plate having: a circularly polarizing plate defined above; and a
pressure sensitive adhesive layer provided on at least one of
opposite surfaces of the circularly polarizing plate.
[0012] Further, according to the invention, there is provided a
liquid-crystal display device having: a liquid-crystal cell; and a
laminated quarter-wave plate or circularly polarizing plate defined
above, or a pressure sensitive adhesive agent-including laminated
quarter-wave plate or circularly polarizing plate defined above and
disposed on at least one of opposite surfaces of the liquid-crystal
cell.
[0013] Next, according to the invention, there is provided a method
of producing a phase retarder (such as a quarter-wave plate or a
half-wave plate) satisfying a relation Nz=(nx-nz)/(nx-ny)>1.05in
which nx and ny are in-plane main refractive indices, and nz is a
thicknesswise refractive index, the method having the step of:
stretching a transparent polymer film with a thickness of 5 to 500
.mu.m by one of tenter lateral stretching and biaxial
stretching.
[0014] Features and advantages of the invention will be evident
from the following detailed description of the preferred
embodiments described in conjunction with the attached
drawings.
BRIEF DESCRIPTION OF THE DRAWINGS
[0015] In the attached drawings:
[0016] FIG. 1 is a sectional view of an embodiment of a
liquid-crystal display device; and
[0017] FIG. 2 is a sectional view of another embodiment of a
liquid-crystal display device.
DETAILED DESCRIPTION OF THE PREFERRED EMBODIMENTS
[0018] As shown in FIGS. 1 and 2, the laminated quarter-wave plate
1 according to the invention has a laminate of a quarter-wave plate
2 and a half-wave plate 3. The quarter-wave plate 2 and the
half-wave plate 3 are laminated on each other so that directions of
in-plane slow axes intersect each other, and each of the
quarter-wave plate 2 and the half-wave plate 3 satisfies a relation
Nz=(nx-nz)/(nx-ny)>1.05 in which nx and ny are in-plane main
refractive indices, and nz is a thicknesswise refractive index. nx
is an in-plane refractive index in the direction in which the
in-plane refractive index becomes maximum within the plane of the
plate, and ny is an in-plane refractive index in the direction
orthogonal to the direction of nx.
[0019] Materials of the quarter-wave plate and the half-wave plate
are not particularly limited but materials excellent in
birefringence controllability, transparency and heat resistance may
be preferably used. Polymer films produced by an extrusion or cast
film-forming method are preferably used from the point of view of
reducing variation in birefringence. Examples of polymer for
forming such polymer films include polyolefin (polyethylene,
polypropylene, etc.), polynorbornene-based polymer, polyvinyl
chloride, polystyrene, polyacrylonitrile, polycarbonate, polyester,
polysulfone, polyallylate, polyvinyl alcohol, polymethacrylate
ester, polyacrylate ester, cellulose ester, and so on.
Particularly, polynorbornene-based polymer, polycarbonate,
polyester, polysulfone and polyallylate are preferred from the
point of view of birefringence controllability, birefringence
uniformity, transparency and heat resistance. As each of the
polymer films, a film having a thickness of not larger than 3 mm,
particularly in a range of from 1 .mu.m to 1 mm, more particularly
in a range of from 5 to 500 .mu.m is generally used from the point
of view of obtaining a homogeneous stretched film by a stable
stretching process.
[0020] The method of generating a retardation is not particularly
limited. A general stretching process such as uniaxial stretching
or biaxial stretching can be used as the method. To obtain a
quarter-wave plate and a half-wave plate satisfying the relation
Nz=(nx-nz)/(nx-ny)>1.05, tenter lateral stretching or biaxial
stretching is preferably used. The biaxial stretching may be either
simultaneous biaxial stretching using a full tentering method or
successive biaxial stretching using a roll tentering method.
Stretching conditions such as stretching temperature, stretching
rate, stretching magnification, etc. are not determined because
optimal conditions vary in accordance with the kind of the polymer
film used, the thickness thereof, and so on. It is however
preferable that the stretching temperature is near to or not lower
than the glass transition point (Tg) of the polymer film used. The
stretching magnification varies in accordance with the stretching
method, etc. but it is preferable that the polymer film is
stretched laterally by a stretching magnification of 50 to 200% or
biaxially stretched by a stretching magnification of 50 to 200% in
a main stretching direction to thereby form a quarter-wave plate or
a half-wave plate. Incidentally, the "stretching magnification of
100%" means a state in which a non-stretched film is stretched to
twice.
[0021] The thickness of the quarter-wave plate or the half-wave
plate is not particularly limited and can be determined suitably in
accordance with the purpose of use. Generally, the thickness is set
to be not larger than 1 mm, preferably in a range of from 1 to 500
.mu.m, more preferably in a range of from 5 to 300 .mu.m. The
quarter-wave plate and the half-wave plate produced in this manner
are laminated on each other so that the in-plane slow axes of the
two plates intersect each other. Thus, a laminated quarter-wave
plate is obtained. The laminating method is not particularly
limited. Any suitable material such as an adhesive agent, or a
pressure sensitive adhesive agent can be used if the material is
high in transparency.
[0022] The material of a polarizer 4 in FIG. 2 is not particularly
limited. Any known material in the related art can be used as the
material of the polarizer. Generally, the polarizer is provided as
a plate having a polarization film and a transparent protective
film as a protective layer bonded to one or each of opposite
surfaces of the polarization film through a suitable adhesive
layer.
[0023] The material of the polarization film is not particularly
limited. Examples of the material of the polarization film include:
a polarization film obtained by stretching a hydrophilic polymer
film such as a polyvinyl alcohol (PVA)-based film, a partially
formalized polyvinyl alcohol-based film or an ethylene-vinyl
acetate copolymer-based partially saponified film after adsorbing
iodine and/or dichromatic dye onto the hydrophilic polymer film;
and a polarization film formed from a polyene-oriented film such as
a dehydrate of polyvinyl alcohol or dehydrochlorinate of polyvinyl
chloride. Especially, a polyvinyl alcohol-based film containing
iodine or dichromatic dye adsorbed thereon and oriented is
preferred. The thickness of the polarization film is not
particularly limited but is generally preferably set to be in a
range of from 1 to 80 .mu.m, particularly in a range of from 2 to
40 .mu.m.
[0024] A suitable transparent film can be used as the material of
the protective film provided as a transparent protective layer
provided on one or each of opposite surfaces of the polarization
film. Especially, a film of a polymer excellent in transparency,
mechanical strength, thermal stability and moisture sealability is
preferably used. Examples of the polymer include: an acetate-based
resin such as triacetyl cellulose; and a polymer selected from the
materials listed above in the description of the quarter-wave plate
and the half-wave plate. The polymer is, however, not limited
thereto. The protective layer may contain fine particles so that a
surface of the protective layer is formed to have a finely
roughened structure.
[0025] The transparent protective film which can be particularly
preferably used from the point of view of polarizing
characteristic, durability, etc. is a triacetyl cellulose film
having a surface saponified with alkali. The thickness of the
transparent protective film is optional. Generally, the thickness
of the transparent protective film is set to be not larger than 500
.mu.m, preferably in a range of from 5 to 300 .mu.m, more
preferably in a range of from 5 to 150 .mu.m for the purpose of
reducing the thickness and size of the polarizer. Incidentally,
when transparent protective films are provided on opposite surfaces
of the polarization film, transparent protective films of polymers
different between the front and the rear may be used.
[0026] The process of bonding the polarization film and the
transparent protective film as a protective layer to each other is
not particularly limited. For example, the bonding process can be
performed through an adhesive agent of an acryl-based polymer or a
vinyl alcohol-based polymer or through an adhesive agent at least
containing an aqueous crosslinking agent for the vinyl
alcohol-based polymer such as boric acid, borax, glutaraldehyde,
melamine or oxalic acid. By such an adhesive agent, the transparent
protective film can be prevented from being peeled because of the
influence of humidity and heat, so that the transparent protective
film can be formed as a film excellent in light transmittance and
the degree of polarization. Such an adhesive layer is formed as a
layer obtained by applying an aqueous solution and drying the
aqueous solution in accordance with necessity. When the aqueous
solution is prepared, another additive and a catalyst such as acid
may be mixed with the aqueous solution. Particularly an adhesive
agent made from polyvinyl alcohol is preferably used because the
adhesive agent is excellent in adhesion to a PVA film.
[0027] The method of laminating the polarizer 4 and the laminated
quarter-wave plate 1 to produce a circularly polarizing plate 5 in
FIG. 2 is not particularly limited. A suitable material such as an
adhesive agent or a pressure sensitive adhesive agent can be used
if the material is high in transparency. The quarter- or half-wave
plate may be used as a layer for protecting a polarizer so that the
other, half- or quarter-wave plate can be bonded and laminated on
the polarizer through an adhesive agent or a pressure sensitive
adhesive agent. Then, only an ordinary protective film is bonded to
the other side on which the half- or quarter-wave plate is not
bonded. In the case of such a method, a wave plate satisfying the
relation Nz=(nx-nz)/(nx-ny)>1.05 is used as the protective film
provided on one side of the polarizer.
[0028] The adhesive agent (pressure sensitive adhesive agent) used
for lamination of the quarter-wave plate and the half-wave plate or
lamination of the laminated quarter-wave plate and the polarizer is
not particularly limited. An adhesive agent not requiring any
high-temperature process for curing or drying or an adhesive agent
not requiring any long-term curing or drying process is preferably
used from the point of view of preventing the optical
characteristic of the polarizer from changing. Further, an adhesive
agent prevented from peeling under heating and humidifying
conditions is preferably used. For example, a transparent
pressure-sensitive adhesive agent such as an acryl-based adhesive
agent, silicone-based adhesive agent, a polyester-based adhesive
agent, a polyurethane-based adhesive agent, a polyether-based
adhesive agent or a rubber-based adhesive agent may be used.
[0029] A pressure sensitive adhesive layer 6 may be provided on the
laminated quarter-wave plate 1 or the circularly polarizing plate 5
so that the laminated quarter-wave plate 1 or the circularly
polarizing plate 5 can be bonded to another member such as a
liquid-crystal cell 7. The pressure sensitive adhesive layer 6 can
be formed from a suitable pressure sensitive adhesive agent
according to the related art such as the acryl-based trackifier.
When the pressure sensitive adhesive layer 6 provided on the
laminated quarter-wave plate 1 or the circularly polarizing plate 5
is exposed to the surface, the pressure sensitive adhesive layer 6
may be preferably covered with a separator for the purpose of
preventing contamination until the pressure sensitive adhesive
layer 6 is put into practical use. The separator can be formed from
a suitable leaf body of a material selected from materials listed
in the description of the transparent protective film. If
necessary, a release coat made from a suitable releasant such as a
silicone-based releasant, a long-chain alkyl-based releasant, a
fluorine-based releasant or a molybdenum sulfide releasant may be
provided on the suitable leaf body.
[0030] Incidentally, each of layers such as the laminated
quarter-wave plate, the polarization film, the transparent
protective layer, the pressure sensitive adhesive layer, etc., may
be treated with an ultraviolet absorbent such as a salicylic
ester-based compound, a benzophenol-based compound, a
benzotriazole-based compound, a cyanoacrylate-based compound or a
nickel complex salt-based compound so that the layer has
ultraviolet absorptive power.
[0031] The laminated quarter-wave plate or the circularly
polarizing plate according to the invention is effectively used as
a quarter-wave plate or a circularly polarizing plate in a
multi-domain VA-LCD. In practical use, the laminated quarter-wave
plate or the circularly polarizing plate may be formed successively
and individually by lamination in the process for production of
each display device. Alternatively, the laminated quarter-wave
plate or the circularly polarizing plate may be laminated in
advance. In this case, there is an advantage in that both quality
stability and laminating workability are so excellent that
efficiency in production of each display device can be
improved.
[0032] The laminated quarter-wave plate or the circularly
polarizing plate according to the invention can be used for forming
various kinds of liquid-crystal display devices 8. Particularly
light leakage caused by birefringence of a liquid-crystal cell,
light leakage generated in cross-Nicol polarizers and color
shifting which have heretofore occurred in a VA mode liquid-crystal
display device can be reduced. Thus, a liquid-crystal display
device having a wide viewing angle in all azimuths can be obtained.
Incidentally, when the laminated quarter-wave plate or the
circularly polarizing plate according to the invention is mounted
on a liquid-crystal cell, it is necessary to perform design in
consideration of birefringence based on orientation of liquid
crystal and it is therefore necessary to suitably adjust the
retardation value of the wave plate and the angle of intersection
between the wave plate and the polarizer.
[0033] Further, for formation of the liquid-crystal display device,
at least one layer of a suitable component such as a prism array
sheet, a lens array sheet, a light-diffusing plate or a backlight
unit may be disposed in a suitable position.
[0034] The invention will be described below more specifically in
connection with Examples 1 and 2 and Comparative Examples 1 to
3.
EXAMPLE 1
[0035] A 100 .mu.m-thick norbornene film (trade name "Arton Film"
made by JSR Corporation) was stretched widthwise by 130% by a
tenter at a temperature of 175.degree. C. to thereby obtain a 44
.mu.m-thick quarter-wave plate. On the other hand, the same 100
.mu.m-thick norbornene film as described above was successively
biaxially stretched lengthwise by 90% and widthwise by 5% by a roll
tentering system at a temperature of 175.degree. C. to thereby
obtain a 70 .mu.m-thick half-wave plate. Then, the quarter-wave
plate and the half-wave plate were laminated on each other so that
the slow axis of the quarter-wave plate makes 20.degree. in a
counterclockwise direction whereas the slow axis of the half-wave
plate makes 67.5.degree. in a clockwise direction. Thus, a
laminated quarter-wave plate was obtained. Finally, linearly
polarizing plates (trade name "NRF" made by Nitto Denko
Corporation) were laminated on the laminated phase retarder so that
the absorption axes of the linearly polarizing plates make
0.degree. and 90.degree. respectively. Thus, a right-hand
circularly polarizing plate and a left-hand circularly polarizing
plate were obtained.
Comparative Example 1
[0036] A 100 .mu.m-thick norbornene film the same as used in
Example 1 was stretched lengthwise by 25% at a temperature of
175.degree. C. to thereby obtain a 91 .mu.m-thick quarter-wave
plate. On the other hand, the same 100 .mu.m-thick norbornene film
as described above was stretched lengthwise by 80% at a temperature
of 175.degree. C. to thereby obtain a 78 .mu.m-thick half-wave
plate. Then, the quarter-wave plate and the half-wave plate were
laminated on each other so that the slow axis of the quarter-wave
plate makes 20.degree. in a counterclockwise direction whereas the
slow axis of the half-wave plate makes 67.5.degree. in a clockwise
direction. Thus, a laminated quarter-wave plate was obtained.
Finally, linearly polarizing plates the same as used in Example 1
were laminated on the laminated phase retarder so that the
absorption axes of the linearly polarizing plates make 0.degree.
and 90.degree. respectively. Thus, a right-hand circularly
polarizing plate and a left-hand circularly polarizing plate were
obtained.
[0037] Values of Nz in the quarter-wave plates and the half-wave
plates obtained in Example 1 and Comparative Example 1 were
measured with KOBRA-21ADH which was made by Oji Scientific
Instruments and which used a parallel nicol rotary method as a
principle. Results of the measurement were as shown in Table 1.
1 TABLE 1 Nz (quarter-wave Nz (half-wave plate) plate) Example 1
1.50 1.15 Comparative Example 1 1.01 1.02
EXAMPLE 2
[0038] The right-hand circularly polarizing plate and the left-hand
circularly polarizing plate obtained in Example 1 were disposed on
opposite sides of a multi-domain VA type cell to thereby obtain a
liquid-crystal display device.
Comparative Example 2
[0039] The right-hand circularly polarizing plate and the left-hand
circularly polarizing plate obtained in Comparative Example 1 were
disposed on opposite sides of a multi-domain VA type cell to
thereby obtain a liquid-crystal display device.
Comparative Example 3
[0040] Linearly polarizing plates (the same as used in Example 1)
were disposed on opposite sides of a multi-domain VA type cell to
thereby obtain a liquid-crystal display device.
[0041] In each of the liquid-crystal display devices obtained in
Example 2 and Comparative Examples 2 and 3, frontal luminance and
viewing angles in Co.gtoreq.10 in accordance with azimuth angles
.PHI. of 45.degree., 135.degree., 225.degree. and 315.degree. were
measured with EZ-contrast (made by Eldim). Incidentally, luminance
was normalized on the assumption that luminance in Comparative
Example 3 was regarded as 100. Results of the measurement were as
shown in Table 2.
2 TABLE 2 Frontal Viewing angle Luminance .PHI. = 45.degree.
135.degree. 225.degree. 315.degree. Example 2 130 60 65 60 65
Comparative 130 40 40 40 40 Example 2 Comparative 100 30 30 30 30
Example 3
[0042] It is obvious from results in Table 2 that frontal luminance
is improved and a liquid-crystal display device with a wide viewing
angle is obtained when circularly polarizing plates using laminated
quarter-wave plates according to the invention are used in the
liquid-crystal display device.
[0043] As described above, the laminated quarter-wave plate and the
circularly polarizing plate according to the invention can be
produced easily and inexpensively, so that productivity is
excellent. When the laminated quarter-wave plate or the circularly
polarizing plate is mounted on a liquid-crystal display device,
frontal luminance can be improved so that the liquid-crystal
display device can be achieved as a liquid-crystal display device
with a wide viewing angle. Moreover, when the laminated
quarter-wave plate or the circularly polarizing plate is mounted on
a VA mode liquid-crystal display device, the liquid-crystal display
device can be provided as a VA-LCD excellent in visibility.
Accordingly, the invention is of great industrial value.
[0044] This invention should not be limited to the embodiments
described above. Various modifications can be included in this
invention within a range which can be easily realized by those
skilled in the art without departing from the spirit of the scope
of claim.
* * * * *